Pilot valves of the block and bleed type commonly use a pressure balance spool valve which is shiftable, responsive to a change in a controlled, sensed pressure to apply or exhaust a control pressure to a motor valve, thereby controlling the latter. Thus the valve element is normally urged to one position by a spring whose force is opposed by the fluid pressure to be controlled acting on a piston to urge the valve element toward a second position. Pressure sensing valves of this type generally incorporate as part of the valve element, or separate from the valve element and engaging the valve element, a piston surface within a piston chamber and exposed to the sensing fluid pressure so that the area of the piston member determines the force at which a specified pressure will overcome the spring force opposing the fluid pressure to urge the valve element toward its second position. For a specified piston area pressure surface and a specified spring, a pressure sensor pilot valve has a specified range of pressure to which the "trip" pressure may be adjusted. In order to accommodate different values of pressure ranges, pilot valves incorporated the use of a number of springs of varying compression force and/or different piston and housing assemblies having varying piston surface areas. This practice necessitated interchanging these various springs and/or piston and housing assemblies to accommodate a certain specific range of "trip" pressure in order for the sensing pilot valve to function properly.